[SCSI] 53c700: Allow setting burst length

This is a patch, which allows not only disabling bursting but to specify
different burst lenghts. This feature is needed to get the 53c700 driver
working for the onboard SCSI controller of SNI RM machines, which only
work reliably with a 4 word burst length.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

4 files changed, 24 insertions, 4 deletions

diff --git a/drivers/scsi/53c700.c b/drivers/scsi/53c700.c
index 68103e508db..88e061d13d0 100644
--- a/drivers/scsi/53c700.c
+++ b/drivers/scsi/53c700.c
@@ -667,12 +667,30 @@ NCR_700_chip_setup(struct Scsi_Host *host)
         __u8 min_xferp = (hostdata->chip710 ? NCR_710_MIN_XFERP : NCR_700_MIN_XFERP);
 
         if(hostdata->chip710) {
-                __u8 burst_disable = hostdata->burst_disable
-                        ? BURST_DISABLE : 0;
+                __u8 burst_disable = 0;
+                __u8 burst_length = 0;
+
+                switch (hostdata->burst_length) {
+                        case 1:
+                                burst_length = BURST_LENGTH_1;
+                                break;
+                        case 2:
+                                burst_length = BURST_LENGTH_2;
+                                break;
+                        case 4:
+                                burst_length = BURST_LENGTH_4;
+                                break;
+                        case 8:
+                                burst_length = BURST_LENGTH_8;
+                                break;
+                        default:
+                                burst_disable = BURST_DISABLE;
+                                break;
+                }
                 dcntl_extra = COMPAT_700_MODE;
 
                 NCR_700_writeb(dcntl_extra, host, DCNTL_REG);
-                NCR_700_writeb(BURST_LENGTH_8  | hostdata->dmode_extra,
+                NCR_700_writeb(burst_length | hostdata->dmode_extra,
                                host, DMODE_710_REG);
                 NCR_700_writeb(burst_disable | (hostdata->differential ? 
                                                 DIFF : 0), host, CTEST7_REG);
diff --git a/drivers/scsi/53c700.h b/drivers/scsi/53c700.h
index f38822db421..841e1bb27d5 100644
--- a/drivers/scsi/53c700.h
+++ b/drivers/scsi/53c700.h
@@ -203,7 +203,7 @@ struct NCR_700_Host_Parameters {
         __u32   force_le_on_be:1;
 #endif
         __u32   chip710:1;      /* set if really a 710 not 700 */
-        __u32   burst_disable:1;        /* set to 1 to disable 710 bursting */
+        __u32   burst_length:4; /* set to 0 to disable 710 bursting */
 
         /* NOTHING BELOW HERE NEEDS ALTERING */
         __u32   fast:1;         /* if we can alter the SCSI bus clock
diff --git a/drivers/scsi/lasi700.c b/drivers/scsi/lasi700.c
index f0871c3ac3d..2aae1b081fc 100644
--- a/drivers/scsi/lasi700.c
+++ b/drivers/scsi/lasi700.c
@@ -123,6 +123,7 @@ lasi700_probe(struct parisc_device *dev)
                 hostdata->force_le_on_be = 0;
                 hostdata->chip710 = 1;
                 hostdata->dmode_extra = DMODE_FC2;
+                hostdata->burst_length = 8;
         }
 
         host = NCR_700_detect(&lasi700_template, hostdata, &dev->dev);
diff --git a/drivers/scsi/sim710.c b/drivers/scsi/sim710.c
index 551baccec52..018c65f73ac 100644
--- a/drivers/scsi/sim710.c
+++ b/drivers/scsi/sim710.c
@@ -123,6 +123,7 @@ sim710_probe_common(struct device *dev, unsigned long base_addr,
         hostdata->differential = differential;
         hostdata->clock = clock;
         hostdata->chip710 = 1;
+        hostdata->burst_length = 8;
 
         /* and register the chip */
         if((host = NCR_700_detect(&sim710_driver_template, hostdata, dev))